Modulation of conjunctival goblet cell differentiation by immunoregulatory cells: This project will investigate the role of local immunoregulatory pathways on conjunctival epithelial homeostasis and the response of the conjunctival epithelium to the desiccating stress of dry eye. We hypothesize that dry eye causes a decrease in the number of CD8+ and 34T intraepithelial lymphocytes (IEL) in the conjunctiva, resulting in decreased levels of immunoregulatory cytokines (e.g. TGF-22) and goblet-cell supporting factors (e.g. keratinocyte growth factor). This facilitates migration of interferon-gamma (IFN-?) producing CD4+ T cells into the conjunctival epithelium resulting in a cytokine imbalance that favors cornified envelope production, rather than goblet cell differentiation by the conjunctival epithelium. In Aim 1, the predominant subset of 34T cells in conjunctival biopsies from normal mouse eyes will be characterized by immunostaining and following in vitro expansion, the cytokine and growth factor profile of 34 and CD8 IEL will be evaluated by a multiplex immunobead assay, real-time PCR and microarray. The objective of Aim 2 is to investigate the role of IEL on survival of conjunctiva goblet cells after desiccating stress. To accomplish this, the resident density of CD8+ and 34 IELs will be evaluated prior to and after 5 and 10 days of experimental dry eye in C57BL/6 mice and in TCR-/- mice (34 T cell knock-out), CD8-/- mice and dominant negative fibroblast growth factor receptor 2 (dnFGFR2) transgenic mice. The time course of expression of KGF and TGF-22 will be evaluated. Co-localization of these factors to 34T and CD8+ T cells will be accomplished by dual label immunohistochemistry. The consequences of loss of 34T and CD8+ T cells and KGF and TGF-22 on conjunctival homeostasis will be confirmed by evaluating goblet cell and CD4+ cell density and expression of the goblet cell mucin MUC5AC and metaplasia marker small proline rich residue 2 protein (SPRR-2) in conjunctival sections from normal and dry eye mice. KGF and TGF-22 will be overexpressed using adenoviral vectors with the intent of preventing the goblet cell loss that occurs in dry eye. PUBLIC HEALTH RELEVANCE. This proposal will investigate the function of immuno-regulatory cells in the conjunctiva of the eye surface with regard to maintaining homeostasis and responding to desiccating environmental stress. These studies will provide new information about natural mechanisms to control inflammation on the ocular surface and may provide new insight into treating ocular surface inflammatory diseases.